Neurodevelopmental outcome at 12 and 18 months in late preterm infants

Abstract

Background Late-preterms represent the 70% of the whole preterm population and are reported to be at higher risk for mortality and morbidity than term infants. Aims To assess neurodevelopmental outcome in low-risk late-preterm infants at 12 and 18 months corrected age, to compare results of corrected and uncorrected age to those of term-born infants, to analyse the possible influence of gender on outcome. Methods Sixty-one healthy infants born between 33 and 36 weeks gestational age without major brain lesions were assessed at 12 and 18 months corrected age using the Bayley II scale. A control group of 60 low-risk term born infants underwent the same assessment. Results At 12 and 18 months corrected age late preterms showed a mean mental developmental index (MDI) similar to term infants. Comparing the results of the uncorrected age with term infants, the scores were significantly lower at both 12 and 18 months. No gender differences were observed in term-born infants, while male late-preterm infants showed lower MDI than peer females at both ages. Conclusions When correcting age for prematurity late-preterms have similar MDI scores to those obtained in term-born infants at 12 and 18 months. In contrast, when using chronological age there is a number of infants with low MDI. As cognitive abnormalities are reported at school age in late preterm infants, our findings raise the question on whether the results obtained using scores uncorrected for age may early identify the infants who will show cognitive difficulties at school age.